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.TH GETPWNAM 3C "Feb 25, 2017"
.SH NAME
getpwnam, getpwnam_r, getpwent, getpwent_r, getpwuid, getpwuid_r, setpwent,
endpwent, fgetpwent, fgetpwent_r \- get password entry
.SH SYNOPSIS
.LP
.nf
#include <pwd.h>

\fBstruct passwd *\fR\fBgetpwnam\fR(\fBconst char *\fR\fIname\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBgetpwnam_r\fR(\fBconst char *\fR\fIname\fR, \fBstruct passwd *\fR\fIpwd\fR,
     \fBchar *\fR\fIbuffer\fR, \fBint\fR \fIbuflen\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBgetpwent\fR(\fBvoid\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBgetpwent_r\fR(\fBstruct passwd *\fR\fIpwd\fR, \fBchar *\fR\fIbuffer\fR,
     \fBint\fR \fIbuflen\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBgetpwuid\fR(\fBuid_t\fR \fIuid\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBgetpwuid_r\fR(\fBuid_t\fR \fIuid\fR, \fBstruct passwd *\fR\fIpwd\fR,
    \fBchar *\fR\fIbuffer\fR, \fBint\fR  \fIbuflen\fR);
.fi

.LP
.nf
\fBvoid\fR \fBsetpwent\fR(\fBvoid\fR);
.fi

.LP
.nf
\fBvoid\fR \fBendpwent\fR(\fBvoid\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBfgetpwent\fR(\fBFILE *\fR\fIf\fR);
.fi

.LP
.nf
\fBstruct passwd *\fR\fBfgetpwent_r\fR(\fBFILE *\fR\fIf\fR, \fBstruct passwd *\fR\fIpwd\fR,
     \fBchar *\fR\fIbuffer\fR, \fBint\fR \fIbuflen\fR);
.fi

.SS "Standard conforming"
.LP
.nf
cc [ \fIflag\fR...] \fIfile\fR... \fB-D_POSIX_PTHREAD_SEMANTICS\fR [ \fIlibrary\fR... ]

\fBint\fR \fBgetpwnam_r\fR(\fBconst char *\fR\fIname\fR, \fBstruct passwd *\fR\fIpwd\fR, \fBchar *\fR\fIbuffer\fR,
     \fBsize_t\fR \fIbufsize\fR, \fBstruct passwd **\fR\fIresult\fR);
.fi

.LP
.nf
\fBint\fR \fBgetpwuid_r\fR(\fBuid_t\fR \fIuid\fR, \fBstruct passwd *\fR\fIpwd\fR, \fBchar *\fR\fIbuffer\fR,
     \fBsize_t\fR \fIbufsize\fR, \fBstruct passwd **\fR\fIresult\fR);
.fi

.SH DESCRIPTION
.LP
These functions are used to obtain password entries. Entries can come from any
of the sources for \fBpasswd\fR specified in the \fB/etc/nsswitch.conf\fR file
(see \fBnsswitch.conf\fR(5)).
.sp
.LP
The \fBgetpwnam()\fR function searches for a password entry with the login name
specified by the character string parameter \fIname\fR.
.sp
.LP
The \fBgetpwuid()\fR function searches for a password entry with the (numeric)
user \fBID\fR specified by the \fIuid\fR parameter.
.sp
.LP
The \fBsetpwent()\fR, \fBgetpwent()\fR, and \fBendpwent()\fR functions are used
to enumerate password entries from the database. The \fBsetpwent()\fR function
sets (or resets) the enumeration to the beginning of the set of password
entries. This function should be called before the first call to
\fBgetpwent()\fR. Calls to \fBgetpwnam()\fR and \fBgetpwuid()\fR leave the
enumeration position in an indeterminate state. Successive calls to
\fBgetpwent()\fR return either successive entries or a null pointer, indicating
the end of the enumeration.
.sp
.LP
The \fBendpwent()\fR function may be called to indicate that the caller expects
to do no further password retrieval operations; the system may then  close the
password file, deallocate resources it was using, and so forth.  It is still
allowed, but possibly less efficient, for the process to call more password
functions after calling \fBendpwent()\fR.
.sp
.LP
The \fBfgetpwent()\fR function, unlike the other functions above, does not use
\fBnsswitch.conf\fR but reads and parses the next line from the stream \fIf\fR,
which is assumed to have the format of the \fBpasswd\fR file.  See
\fBpasswd\fR(5).
.SS "Reentrant Interfaces"
.LP
The \fBgetpwnam()\fR, \fBgetpwuid()\fR, \fBgetpwent()\fR, and \fBfgetpwent()\fR
functions use thread-specific data storage that is reused in each call to one
of these functions by the same thread, making them safe to use but not
recommended for multithreaded applications.
.sp
.LP
The parallel functions \fBgetpwnam_r()\fR, \fBgetpwuid_r()\fR,
\fBgetpwent_r()\fR, and \fBfgetpwent_r()\fR provide reentrant interfaces for
these operations.
.sp
.LP
Each reentrant interface performs the same operation as its non-reentrant
counterpart, named by removing the "\|_r\|" suffix. The reentrant interfaces,
however, use buffers supplied by the caller to store returned results instead
of using thread-specific data that can be overwritten by each call. They are
safe for use in both single-threaded and multithreaded applications.
.sp
.LP
Each reentrant interface takes the same parameters as its non-reentrant
counterpart, as well as the following additional parameters. The \fIpwd\fR
parameter must be a pointer to a \fBstruct passwd\fR structure allocated by the
caller. On successful completion, the function returns the password entry in
this structure. The parameter \fIbuffer\fR is a pointer to a buffer supplied by
the caller, used as storage space for the password data. All pointers within
the returned \fBstruct passwd\fR \fIpwd\fR point to data stored within this
buffer; see \fBpasswd Structure\fR below. The buffer must be large enough to
hold all the data associated with the password entry. The parameter
\fIbuflen\fR (or \fIbufsize\fR for the standard-conforming versions; see
\fBstandards\fR(7)) should give the size in bytes of \fIbuffer\fR. The maximum
size needed for this buffer can be determined with the
{\fB_SC_GETPW_R_SIZE_MAX\fR} \fBsysconf\fR(3C) parameter. The
standard-conforming versions place a pointer to the modified \fIpwd\fR
structure in the \fIresult\fR parameter, instead of returning a pointer to this
structure. A null pointer is returned at the location pointed to by
\fIresult\fR on error or if the requested entry is not found.
.sp
.LP
For enumeration in multithreaded applications, the position within the
enumeration is a process-wide property shared by all threads. The
\fBsetpwent()\fR function can be used in a multithreaded application but resets
the enumeration position for all threads.  If multiple threads interleave calls
to \fBgetpwent_r()\fR, the threads will enumerate disjoint subsets of the
password database.
.sp
.LP
Like their non-reentrant counterparts, \fBgetpwnam_r()\fR and
\fBgetpwuid_r()\fR leave the enumeration position in an indeterminate state.
.SS "passwd Structure"
.LP
Password entries are represented by the \fBstruct passwd\fR structure defined
in <\fBpwd.h\fR>:
.sp
.in +2
.nf
struct passwd {
    char *pw_name;      /* user's login name */
    char *pw_passwd;    /* no longer used */
    uid_t pw_uid;       /* user's uid */
    gid_t pw_gid;       /* user's gid */
    char *pw_age;       /* not used */
    char *pw_comment;   /* not used */
    char *pw_gecos;     /* typically user's full name */
    char *pw_dir;       /* user's home dir */
    char *pw_shell;     /* user's login shell */
};
.fi
.in -2

.sp
.LP
The \fBpw_passwd\fR member should not be used as the encrypted password for the
user; use \fBgetspnam()\fR or \fBgetspnam_r()\fR instead. See
\fBgetspnam\fR(3C).
.SH RETURN VALUES
.LP
The \fBgetpwnam()\fR, \fBgetpwnam_r()\fR, \fBgetpwuid()\fR, and
\fBgetpwuid_r()\fR functions each return a pointer to a \fBstruct passwd\fR if
they successfully locate the requested entry. A null pointer is returned if the
requested entry is not found, or an error occurs. On error, \fBerrno\fR is set
to indicate the error.
.sp
.LP
Applications wishing to check for error situations should set \fBerrno\fR to 0
before calling \fBgetpwnam()\fR, \fBgetpwnam_r()\fR, \fBgetpwuid()\fR,
\fBgetpwuid_r()\fR, \fBgetpwent()\fR, \fBgetpwent_r()\fR, \fBfgetpwent()\fR,
and \fBfgetpwent_r()\fR. If these non-reentrant functions return a null pointer
and \fBerrno\fR is non-zero, an error occurred.
.sp
.LP
The standard-conforming functions \fBgetpwnam_r()\fR and \fBgetpwuid_r()\fR can
return \fB0\fR even on an error, particularly in the case where the requested
entry is not found. The application needs to check the return value and that
the \fIpwd\fR pointer is non-null. Otherwise, an error value is returned to
indicate the error.
.sp
.LP
The \fBgetpwent()\fR, \fBgetpwent_r()\fR, \fBfgetpwent()\fR, and
\fBfgetpwent_r()\fR functions each return a pointer to a \fBstruct passwd\fR if
they successfully enumerate an entry; otherwise they return a null pointer on
end-of-file or error. On error, \fBerrno\fR is set to indicate the error.
.sp
.LP
See \fBIntro\fR(2) for the proper usage and interpretation of \fBerrno\fR in
multithreaded applications.
.sp
.LP
The \fBgetpwnam()\fR, \fBgetpwuid()\fR, \fBgetpwent()\fR, and \fBfgetpwent()\fR
functions use thread-specific data storage, so returned data must be copied
before a subsequent call to any of these functions if the data is to be saved.
.sp
.LP
When the pointer returned by the reentrant functions \fBgetpwnam_r()\fR,
\fBgetpwuid_r()\fR, \fBgetpwent_r()\fR, and \fBfgetpwent_r()\fR is non-null, it
is always equal to the \fIpwd\fR pointer that was supplied by the caller.
.SH ERRORS
.LP
The \fBgetpwent_r()\fR, \fBfgetpwent()\fR, and \fBfgetpwent_r()\fR functions
will fail if:
.sp
.ne 2
.na
\fB\fBEIO\fR\fR
.ad
.RS 10n
An I/O error has occurred.
.RE

.sp
.ne 2
.na
\fB\fBERANGE\fR\fR
.ad
.RS 10n
Insufficient storage was supplied by \fIbuffer\fR and \fIbufsize\fR to contain
the data to be referenced by the resulting \fBpasswd\fR structure.
.RE

.sp
.LP
The \fBgetpwent_r()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEMFILE\fR\fR
.ad
.RS 10n
There are {\fBOPEN_MAX\fR} file descriptors currently open in the calling
process.
.RE

.sp
.ne 2
.na
\fB\fBENFILE\fR\fR
.ad
.RS 10n
The maximum allowable number of files is currently open in the system.
.RE

.sp
.LP
The \fBgetpwnam()\fR, \fBgetpwnam_r()\fR, \fBgetpwuid()\fR, \fBgetpwuid_r()\fR,
\fBgetpwent()\fR, \fBsetpwent()\fR, and \fBendpwent()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEIO\fR\fR
.ad
.RS 7n
An I/O error has occurred.
.RE

.sp
.LP
The \fBgetpwnam()\fR, \fBgetpwnam_r()\fR, \fBgetpwuid()\fR, \fBgetpwuid_r()\fR,
\fBgetpwent()\fR, and \fBsetpwent()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEMFILE\fR\fR
.ad
.RS 10n
There are {\fBOPEN_MAX\fR} file descriptors currently open in the calling
process.
.RE

.sp
.ne 2
.na
\fB\fBENFILE\fR\fR
.ad
.RS 10n
The maximum allowable number of files is currently open in the system.
.RE

.sp
.LP
The \fBgetpwnam()\fR, \fBgetpwnam_r()\fR, \fBgetpwuid()\fR, and
\fBgetpwuid_r()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEINTR\fR\fR
.ad
.RS 9n
A signal was caught during the execution of the function call.
.RE

.sp
.LP
The \fBgetpwnam_r()\fR and \fBgetpwuid_r()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBERANGE\fR\fR
.ad
.RS 10n
Insufficient storage was supplied by \fIbuffer\fR and \fIbufsize\fR to contain
the data to be referenced by the resulting \fBpasswd\fR structure.
.RE

.SH USAGE
.LP
Three names associated with the current process can be determined:
\fBgetpwuid\fR(\fBgeteuid()\fR) returns the name associated with the effective
user ID of the process; \fBgetlogin()\fR returns the name associated with the
current login activity; and \fBgetpwuid\fR(\fBgetuid()\fR) returns the name
associated with the real user ID of the process.
.SH ATTRIBUTES
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	See \fBReentrant Interfaces\fR in \fBDESCRIPTION\fR.
_
Standard	See below.
.TE

.sp
.LP
For \fBendpwent()\fR,  \fBgetpwent()\fR,  \fBgetpwnam()\fR,
\fBgetpwnam_r()\fR, \fBgetpwuid()\fR, \fBgetpwuid_r()\fR, and \fBsetpwent()\fR,
see \fBstandards\fR(7).
.SH SEE ALSO
.LP
.BR passwd (1),
.BR yppasswd (1),
.BR Intro (2),
.BR Intro (3),
.BR cuserid (3C),
.BR getgrnam (3C),
.BR getlogin (3C),
.BR getspnam (3C),
.BR nsswitch.conf (5),
.BR passwd (5),
.BR shadow (5),
.BR attributes (7),
.BR standards (7)
.SH NOTES
.LP
When compiling multithreaded programs, see \fBIntro\fR(3).
.sp
.LP
Use of the enumeration interfaces \fBgetpwent()\fR and \fBgetpwent_r()\fR is
discouraged; enumeration is supported for the \fBpasswd\fR file and \fBNIS\fR
but in general is not efficient and might not be supported for all
database sources.  The semantics of enumeration are discussed further in
\fBnsswitch.conf\fR(5).
.sp
.LP
Previous releases allowed the use of `+' and `-' entries in \fB/etc/passwd\fR
to selectively include and exclude \fBNIS\fR entries. The primary usage of
these `+/-' entries is superseded by the name service switch, so the `+/-' form
might not be supported in future releases.
.sp
.LP
If required, the `+/-' functionality can still be obtained for \fBNIS\fR by
specifying \fBcompat\fR as the source for \fBpasswd\fR. See
\fBnsswitch.conf\fR(5).
.sp
.LP
If the `+/-' is used, both \fB/etc/shadow\fR and \fB/etc/passwd\fR should have
the same `+' and `-' entries to ensure consistency between the password and
shadow databases.
.sp
.LP
If a password entry from any of the sources contains an empty \fIuid\fR or
\fIgid\fR field, that entry will be ignored by the files and \fBNIS\fR
name service switch backends, causing the user to appear unknown to
the system.
.sp
.LP
If a password entry contains an empty \fIgecos\fR, \fIhome directory\fR, or
\fIshell\fR field, \fBgetpwnam()\fR and \fBgetpwnam_r()\fR return a pointer to
a null string in the respective field of the \fBpasswd\fR structure.
.sp
.LP
If the shell field is empty, \fBlogin\fR(1) automatically assigns the default
shell.  See \fBlogin\fR(1).
.sp
.LP
Solaris 2.4 and earlier releases provided definitions of the \fBgetpwnam_r()\fR
and \fBgetpwuid_r()\fR functions as specified in POSIX.1c Draft 6. The final
POSIX.1c standard changed the interface for these functions. Support for the
Draft 6 interface is provided for compatibility only and might not be supported
in future releases. New applications and libraries should use the
standard-conforming interface.
.sp
.LP
For POSIX.1c-conforming applications, the \fB_POSIX_PTHREAD_SEMANTICS\fR and
\fB_REENTRANT\fR flags are automatically turned on by defining the
\fB_POSIX_C_SOURCE\fR flag with a value \(>=199506L.
